Chalara fraxinea – ash ‘die back’ fungus

On Thursday 25th October it was widely reported in the media that the fungus Chalara Fraxinea, which has reportedly wiped out 90% of Denmark’s ash population, has been found at two sites in East Anglia. Experts say that the disease could have the same impact on the landscape, if it takes hold, as Dutch elm disease in the 1970s.

The initial outbreak was found in ‘mature ancient woodland and woodland creation areas’ at the Woodland Trust’s Pound Farm woodland in Suffolk, and Norfolk Wildlife Trust’s Lower Wood reserve in Ashwellthorpe.

Visible symptoms include leaf loss and crown dieback in affected trees, and it can lead to tree death. Chalara dieback of ash was immediately listed as a quarantine pathogen under national emergency measures and the Forestry Commission was quick to produce guidance, including help on identifying possible signs of infection.

At the weekend it was announced that on Monday 29th November a ban on the import of trees will come into force. While the environment secretary, Owen Paterson, has denied that ministers were slow to react to the outbreak, a spokesmen from the Horticultural Trades Association disagreed. Tim Briercliffe said, ‘As a trade we’re very frustrated about it, because in 2009 we saw it out in Denmark on trees and we said you should ban imports now. They didn’t do it … and we believe it could be more widespread than perhaps we realise at the moment.‘

If you are a student or a member of Writtle College staff, click here for a list of recent research and review articles on Chalara Fraxinea indexed in the Web of Science database (you will need your network login to access Moodle).